Turn a Trackpad From a Broken Laptop Into a PS/2 Mouse

A friend gave me a broken HP Pavilion laptop. With just a little work, you can remove the trackpad and connect to a PS/2 or 9-pin Serial port . Connect to your PC and use as a simple mouse, or even wire to an Arduino for a unique interface for your project. You can make this project entirely from recycled parts you may just have lying around.

What you need:
-trackpad (I used a Synaptics TM41PUZ307)
-male PS/2 connector with cable (or a 9-pin serial)
-multimeter
-soldering iron
-screwdriver
-razor blade
-electrical tape

Unscrew all the parts to the trackpad. Gently pry up any plastic. I used a hair dryer to help loosen the glue that held the pad to the laptop palm rest.

I removed the PS/2 cable from an old broken keyboard. Alternatively, you can also wire to a 9-pin Serial cable.

Use a multimeter to confirm what the pinout of the PS/2 cable is.
Your wire colors may differ, mine where as follows:
pin1 = DATA = Red
pin3 = GND = Grey
pin4 = +5V = Brown
pin5 = CLK = Yellow

Or, you can wire to a 9-pin Serial port old school mouse style. This is also nice idea to use on a desktop as a secondary mouse.
pin4 = DATA
pin5 = GND
pin7 = CLK
pin8 = +5V

*You could even wire to an AT keyboard.

Use the Internet and search for the pinout of your pad. Or you could use your multimeter again.
Synaptics has a great resource for helping you determine the pinouts of many of their models HERE.
My Synaptics TM41PUZ307 wasn't on the list, but an internet search turned up this:
pin5/6 = GND
pin7/8 = CLK
pin9/10 = DATA
pin11/12 = +5V

I used a razor blade to carefully cut the ribbon cable to connect the 4 wires from the PS/2 cable. A quick dab of some cooling solder (too hot and you'll destroy the cable) and some electrical tape to reinforce.

Ok, you'll want to test first. Just plug it in quickly and the standard windows mouse driver should work just fine. Without installing any drivers, I was able to navigate the mouse, left click, and use the mouse scroll wheel. I mounted it on my keyboard for now. But I plan on eventually using it in an Arduino project. Details on interfacing a trackpad to an Arduino can be found HERE
If you wish to use with USB, you must purchase a "PS/2 to USB Keyboard and Mouse Converter."